Proteins yog cov organic. Cov macromolecular tebchaw no yog tus cwj pwm los ntawm qee qhov muaj pes tsawg leeg thiab decompose rau hauv cov amino acids thaum hydrolysis. Protein molecules tuaj nyob rau hauv ntau yam duab, ntau yam uas yog ua los ntawm ntau yam polypeptide chains. Cov ntaub ntawv hais txog cov qauv ntawm cov protein yog encoded hauv DNA, thiab cov txheej txheem ntawm cov protein synthesis hu ua kev txhais lus.
tshuaj muaj pes tsawg leeg ntawm cov proteins
Nruab nrab cov protein muaj:
- 52% carbon;
- 7% hydrogen;
- 12% nitrogen;
- 21% oxygen;
- 3% sulfur.
Protein molecules yog polymers. Yuav kom nkag siab txog lawv cov qauv, nws yuav tsum paub tias lawv cov monomers, amino acids, yog dab tsi.
Amino acids
Lawv feem ntau muab faib ua ob pawg: tshwm sim tas li thiab qee zaus tshwm sim. Cov qub suav nrog 18 protein monomers thiab 2 ntxiv amides: aspartic thiab glutamic acids. Qee zaum tsuas muaj peb cov kua qaub xwb.
Cov kua qaub no tuaj yeem faib ua ntau txoj hauv kev: los ntawm qhov xwm txheej ntawm cov saw hlau sab lossis tus nqi ntawm lawv cov radicals, lawv kuj tuaj yeem muab faib los ntawm cov pawg CN thiab COOH.
Protein thawj qauv
Qhov sib lawv liag ntawm cov amino acids nyob rau hauv ib txoj saw protein txiav tximnws cov qib tom ntej ntawm lub koom haum, cov khoom thiab kev ua haujlwm. Hom kev sib cog lus tseem ceeb ntawm monomers yog peptide. Nws yog tsim los ntawm kev faib tawm hydrogen los ntawm ib qho amino acid thiab ib pawg OH los ntawm lwm tus.
Thawj theem ntawm lub koom haum ntawm cov protein molecule yog cov kab ke ntawm cov amino acids hauv nws, tsuas yog cov saw hlau uas txiav txim siab cov qauv ntawm cov protein molecules. Nws muaj "skeleton" uas muaj cov qauv tsis tu ncua. Qhov no yog qhov rov ua ntu zus -NH-CH-CO-. Cov kab sib cais yog sawv cev los ntawm cov amino acid radicals (R), lawv cov khoom txiav txim siab cov qauv ntawm cov proteins.
Txawm tias cov qauv ntawm cov protein molecules zoo ib yam, lawv tuaj yeem sib txawv ntawm cov khoom tsuas yog los ntawm qhov tseeb tias lawv cov monomers muaj qhov sib txawv hauv cov saw hlau. Kev npaj ntawm cov amino acids hauv cov protein yog txiav txim siab los ntawm cov noob thiab txiav txim siab qee yam kev ua haujlwm lom neeg rau cov protein. Qhov sib lawv liag ntawm monomers nyob rau hauv molecules lub luag hauj lwm rau tib lub luag hauj lwm yog feem ntau nyob ze ntawm ntau hom. Xws li cov molecules - tib yam lossis zoo sib xws hauv lub koom haum thiab ua haujlwm tib yam hauv ntau hom kab mob - yog homologous proteins. Cov qauv, cov khoom thiab kev ua haujlwm ntawm cov molecules yav tom ntej tau muab tso rau ntawm theem ntawm kev sib txuas ntawm cov amino acid saw.
Qee yam nta
Cov qauv ntawm cov proteins tau kawm tau ntev, thiab kev tshuaj xyuas ntawm lawv cov qauv tseem ceeb tso cai rau peb ua qee qhov dav dav. Feem ntau cov proteins yog cov yam ntxwv ntawm cov muaj nees nkaum amino acids, ntawm uas muaj ntau yam glycine, alanine, aspartic acid, glutamine thiab me ntsis tryptophan, arginine, methionine,histidine. Cov kev zam tsuas yog qee pawg ntawm cov proteins, piv txwv li, histones. Lawv xav tau kev ntim khoom DNA thiab muaj ntau cov histidine.
Thib ob generalization: hauv globular proteins tsis muaj cov qauv dav dav hauv kev hloov ntawm cov amino acids. Tab sis txawm tias polypeptides uas nyob deb ntawm kev ua si lom neeg muaj me me zoo ib yam ntawm cov molecules.
qauv tsev kawm theem nrab
Qib thib ob ntawm lub koom haum ntawm cov saw hlau polypeptide yog nws qhov chaw nyob, uas tau txhawb nqa los ntawm hydrogen bonds. Allocate α-helix thiab β-fold. Ib feem ntawm cov saw hlau tsis muaj cov qauv txiav txim, cov cheeb tsam no hu ua amorphous.
Lub alpha helix ntawm tag nrho cov natural proteins yog sab xis. Sab radicals ntawm cov amino acids nyob rau hauv lub helix ib txwm fim sab nraud thiab nyob rau ntawm opposite sab ntawm nws axis. Yog tias lawv tsis yog-polar, lawv tau muab tso rau ntawm ib sab ntawm cov kauv, ua rau arcs uas tsim cov xwm txheej rau kev sib koom ua ke ntawm cov kab sib txawv.
Beta-folds - elongated spirals - zoo li nyob rau ntawm ib sab ntawm cov protein molecule thiab tsim cov kab uas tsis sib xws thiab tsis sib luag β-pleated txheej.
Tertiary protein qauv
Qib peb ntawm lub koom haum ntawm cov protein molecule yog folding ntawm kauv, folds thiab amorphous seem rau hauv cov qauv compact. Qhov no yog vim muaj kev cuam tshuam ntawm sab radicals ntawm cov monomers nrog ib leeg. Cov kev sib txuas no tau muab faib ua ntau hom:
- hydrogen bonds tsim ntawm polar radicals;
- hydrophobic- nruab nrab ntawm cov tsis-polar R-pab pawg;
- electrostatic rog ntawm kev nyiam (ionic bonds) - nruab nrab ntawm cov pab pawg uas nws cov nqi rov qab;
- disulfide txuas ntawm cysteine radicals.
Hom kawg ntawm daim ntawv cog lus (–S=S-) yog kev sib cuam tshuam. Disulfide txuas ntxiv dag zog rau cov protein, lawv cov qauv ua kom ruaj khov. Tab sis kev sib txuas zoo li no tsis tas yuav tsum tau ua. Piv txwv li, tej zaum yuav muaj cysteine tsawg heev nyob rau hauv cov saw hlau polypeptide, los yog nws cov radicals nyob ze thiab tsim tsis tau ib tug "choj".
Lub koom haum thib plaub
Tsis yog tag nrho cov proteins tsim cov qauv quaternary. Cov qauv ntawm cov proteins ntawm qib plaub yog txiav txim los ntawm tus naj npawb ntawm polypeptide chains (protomers). Lawv sib cuam tshuam los ntawm tib daim ntawv cog lus raws li qib dhau los ntawm lub koom haum, tshwj tsis yog cov txuas hniav disulfide. Ib lub molecule muaj ntau tus protomers, txhua tus muaj nws tus kheej tshwj xeeb (los yog zoo tib yam) tertiary qauv.
Txhua theem ntawm lub koom haum txiav txim siab cov haujlwm uas cov proteins uas tshwm sim yuav ua. Cov qauv ntawm cov proteins ntawm thawj theem ntawm lub koom haum txiav txim siab lawv lub luag haujlwm tom qab hauv lub cell thiab lub cev tag nrho.
Y
Protein Functions
Nws nyuaj txawm xav txog tias lub luag haujlwm ntawm cov proteins hauv tes tseem ceeb npaum li cas. Saum toj no, peb tshuaj xyuas lawv cov qauv. Cov haujlwm ntawm cov proteins ncaj qha nyob ntawm nws.
Ua lub tsev (cov qauv), lawv tsim lub hauv paus ntawm cytoplasm ntawm txhua lub cell nyob. Cov polymers yog cov khoom tseem ceeb ntawm tag nrho cov cell membranes thaumNws yog complex nrog lipids. Qhov no kuj suav nrog kev faib cov cell mus rau hauv cov khoom sib txuas, txhua tus muaj nws cov kev cuam tshuam. Qhov tseeb yog tias txhua txoj hauv kev ntawm cov txheej txheem ntawm tes yuav tsum muaj nws tus kheej, tshwj xeeb tshaj yog pH ntawm nruab nrab plays lub luag haujlwm tseem ceeb. Proteins tsim nyias partitions uas faib lub cell mus rau hauv thiaj li hu ua compartments. Thiab qhov tshwm sim nws tus kheej hu ua compartmentalization.
Lub luag haujlwm catalytic yog tswj hwm txhua qhov kev cuam tshuam ntawm tes. Tag nrho cov enzymes yog ib qho yooj yim los yog complex proteins nyob rau hauv keeb kwm.
Txhua yam kev txav ntawm cov kab mob (kev ua haujlwm ntawm cov leeg nqaij, kev txav ntawm protoplasm hauv lub cell, flickering ntawm cilia hauv protozoa, thiab lwm yam) yog ua los ntawm cov protein. Cov qauv ntawm cov protein tso cai rau lawv txav mus, tsim fibers thiab rings.
Kev thauj mus los yog ntau yam khoom thauj los ntawm cov cell membrane los ntawm cov khoom thauj tshwj xeeb.
Lub luag haujlwm hormonal ntawm cov polymers yog tam sim no meej: ntau cov tshuaj hormones yog cov proteins hauv cov qauv, piv txwv li, insulin, oxytocin.
Spare muaj nuj nqi yog txiav txim siab los ntawm qhov tseeb tias cov proteins tuaj yeem tsim cov nyiaj tso cia. Piv txwv li, qe valgumin, mis nyuj casein, cog noob proteins - lawv khaws ntau cov as-ham.
Tag nrho cov leeg, pob qij txha, pob txha ntawm pob txha, hooves yog tsim los ntawm cov protein, uas coj peb mus rau lawv txoj haujlwm tom ntej - txhawb nqa.
Protein molecules yog cov receptors, ua tiav kev paub txog qee yam tshuaj. Hauv lub luag haujlwm no, glycoproteins thiab lectins tshwj xeeb yog paub.
Qhov tseem ceeb tshaj plawsKev tiv thaiv kab mob - cov tshuaj tiv thaiv kab mob thiab cov kab ke sib txuas los ntawm keeb kwm yog cov proteins. Piv txwv li, cov txheej txheem ntawm cov ntshav txhaws yog raws li kev hloov pauv ntawm cov protein fibrinogen. Sab hauv phab ntsa ntawm txoj hlab pas thiab lub plab yog lined nrog ib txheej tiv thaiv ntawm mucous proteins - licins. Toxins kuj yog cov proteins hauv keeb kwm. Lub hauv paus ntawm daim tawv nqaij uas tiv thaiv lub cev ntawm cov tsiaj yog collagen. Tag nrho cov protein ua haujlwm no tiv thaiv.
Zoo, txoj haujlwm kawg yog kev tswj hwm. Muaj cov proteins uas tswj kev ua haujlwm ntawm genome. Qhov ntawd yog, lawv tswj kev sau thiab txhais lus.
Txawm hais tias lub luag haujlwm ntawm cov protein tseem ceeb npaum li cas, cov qauv ntawm cov protein tau raug tshem tawm los ntawm cov kws tshawb fawb tau ntev. Thiab tam sim no lawv tab tom nrhiav txoj hauv kev tshiab los siv qhov kev paub no.
